Carbohydrate Binding Module 6 (CBM6); many are appended to glycoside hydrolase (GH) family 11 and GH43 xylanase domains. This family includes carbohydrate binding module 6 (CBM6) domains that are appended mainly to glycoside hydrolase (GH) family domains, including GH3, GH11, and GH43 domains. These CBM6s are non-catalytic carbohydrate binding domains that facilitate the strong binding of the GH catalytic modules with their dedicated, insoluble substrates. Examples of proteins having CMB6s belonging to this family are Microbispora bispora GghA, a 1,4-beta-D-glucan glucohydrolase (GH3); Clostridium thermocellum xylanase U (GH11), and Penicillium purpurogenum ABF3, a bifunctional alpha-L-arabinofuranosidase/xylobiohydrolase (GH43). GH3 comprises enzymes with activities including beta-glucosidase (hydrolyzes beta-galactosidase) and beta-xylosidase (hydrolyzes 1,4-beta-D-xylosidase). GH11 family comprises enzymes with xylanase (endo-1,4-beta-xylanase) activity which catalyze the hydrolysis of beta-1,4 bonds of xylan, the major component of hemicelluloses, to generate xylooligosaccharides and xylose. GH43 includes beta-xylosidases and beta-xylanases, using aryl-glycosides as substrates. CBM6 is an unusual CBM as it represents a chimera of two distinct binding sites with different modes of binding: binding site I within the loop regions and binding site II on the concave face of the beta-sandwich fold.

Carbohydrate binding module (family 6).

Cellulose Binding Domain Type IV.

Type I dockerin repeat domain. Bacterial cohesin domains bind to a complementary protein domain named dockerin, and this interaction is required for the formation of the cellulosome, a cellulose-degrading complex. The cellulosome consists of scaffoldin, a noncatalytic scaffolding polypeptide, that comprises repeating cohesion modules and a single carbohydrate-binding module (CBM). Specific calcium-dependent interactions between cohesins and dockerins appear to be essential for cellulosome assembly. This subfamily represents type I dockerins, which are responsible for anchoring a variety of enzymatic domains to the complex.

Dockerin type I repeat. The dockerin repeat is the binding partner of the cohesin domain pfam00963. The cohesin-dockerin interaction is the crucial interaction for complex formation in the cellulosome. The dockerin repeats, each bearing homology to the EF-hand calcium-binding loop bind calcium.

CrystalStructure of a Family 6 Carbohydrate-Binding Module from Clostridium cellulolyticum in complex with xylose [Ruminiclostridium cellulolyticum]

ChainA, CBM6 [Acetivibrio thermocellus],1UXX_X Chain X, Xylanase U [Acetivibrio thermocellus]

Unboundstructure of CsCBM6-3 from Clostridium stercorarium [Thermoclostridium stercorarium]

Structureof CsCBM6-3 from Clostridium stercorarium in complex with xylotriose [Thermoclostridium stercorarium],1O8S_A Structure of CsCBM6-3 from Clostridium stercorarium in complex with cellobiose [Thermoclostridium stercorarium],1OD3_A Structure of CSCBM6-3 From Clostridium stercorarium in complex with laminaribiose [Thermoclostridium stercorarium]

ChainA, Alpha-1,6-mannanase [Niallia circulans],5M77_B Chain B, Alpha-1,6-mannanase [Niallia circulans]

Probable pectate lyase C OS=Aspergillus flavus (strain ATCC 200026 / FGSC A1120 / IAM 13836 / NRRL 3357 / JCM 12722 / SRRC 167) OX=332952 GN=plyC PE=3 SV=1

Probable pectate lyase C OS=Aspergillus oryzae (strain ATCC 42149 / RIB 40) OX=510516 GN=plyC PE=3 SV=1

Probable pectate lyase C OS=Neosartorya fumigata (strain CEA10 / CBS 144.89 / FGSC A1163) OX=451804 GN=plyC PE=3 SV=1

Probable pectate lyase C OS=Emericella nidulans (strain FGSC A4 / ATCC 38163 / CBS 112.46 / NRRL 194 / M139) OX=227321 GN=plyC PE=3 SV=1

Probable pectate lyase C OS=Neosartorya fumigata (strain ATCC MYA-4609 / Af293 / CBS 101355 / FGSC A1100) OX=330879 GN=plyC PE=3 SV=1